Hypoxia-driven sarcoplasmic/endoplasmic reticulum calcium ATPase 2 (SERCA2) downregulation depends on low-density lipoprotein receptor-related protein 1 (LRP1)-signalling in cardiomyocytes.

Abstract

The maintenance of sarcoplasmic reticulum Ca(2+) ATPase (SERCA2) activity is crucial for cardiac function and SERCA2 is dramatically reduced in the heart exposed to hypoxic/ischemic conditions. Previous work from our group showed that hypoxia upregulates the phosphorylated form of the Ca(2+)-dependent nonreceptor protein tyrosine kinase (PTK) proline-rich tyrosine kinase 2 (pPyk2) protein levels in a low-density lipoprotein receptor-related protein (LRP1)-dependent manner. Pyk2 in turn may modulate SERCA2 in cardiomyocytes although this remains controversial. We therefore aimed to investigate the role of LRP1 on hypoxia-induced SERCA2 depletion in cardiomyocytes and to establish LRP1 signalling mechanisms involved. Western blot analysis showed that hypoxia reduced SERCA2 concomitantly with a sustained increase in LRP1 and pPyk2 protein levels in HL-1 cardiomyocytes. By impairing hypoxia-induced Pyk2 phosphorylation and HIF-1α accumulation, LRP1 deficiency prevented SERCA2 depletion and reduction of the sarcoplasmic reticulum calcium content in cardiomyocytes. Moreover, the inhibition of Pyk2 phosphorylation (with the Src-family inhibitor PP2) or the specific silencing of Pyk2 (with siRNA-anti Pyk2) preserved low HIF-1α and high SERCA2 levels in HL-1 cardiomyocytes exposed to hypoxia. We determined that the LRP1/Pyk2 axis represses SERCA2 mRNA expression via HIF-1α since HIF-1α overexpression abolished the protective effect of LRP1 deficiency on SERCA2 depletion. Our findings show a crucial role of LRP1/Pyk2/HIF-1α in hypoxia-induced cardiomyocyte SERCA2 downregulation, a pathophysiological process closely associated with heart failure.

• Authors: Elena Revuelta-López, Roi Cal, Adela Herraiz-Martínez, David de Gonzalo-Calvo, Laura Nasarre, Santiago Roura, Carolina Gálvez-Montón, Antoni Bayes-Genis, Lina Badimon, Leif Hove-Madsen, Vicenta Llorente-Cortés
• Journal: Journal of molecular and cellular cardiology (J Mol Cell Cardiol) Vol. 85 Pg. 25-36 (Aug 2015) ISSN: 1095-8584 [Electronic] England
• PMID: 25968337 (Publication Type: Journal Article)
• Copyright: Copyright © 2015 Elsevier Ltd. All rights reserved.

Chemical References

• Hif1a protein, mouse
• Hypoxia-Inducible Factor 1, alpha Subunit
• Low Density Lipoprotein Receptor-Related Protein-1
• Lrp1 protein, mouse
• Receptors, LDL
• Tumor Suppressor Proteins
• Focal Adhesion Kinase 2
• Ptk2b protein, mouse
• Sarcoplasmic Reticulum Calcium-Transporting ATPases
• Atp2a2 protein, mouse
• Calcium

Topics

• Animals
• Calcium (metabolism)
• Calcium Signaling
• Cell Hypoxia
• Cell Line
• Down-Regulation
• Enzyme Activation
• Focal Adhesion Kinase 2 (metabolism)
• Gene Silencing
• Humans
• Hypoxia-Inducible Factor 1, alpha Subunit (metabolism)
• Low Density Lipoprotein Receptor-Related Protein-1
• Mice
• Myocardial Ischemia (enzymology)
• Myocardium (enzymology)
• Myocytes, Cardiac (metabolism)
• Receptors, LDL (metabolism)
• Sarcoplasmic Reticulum Calcium-Transporting ATPases (genetics, metabolism)
• Tumor Suppressor Proteins (metabolism)